Thermoplastic resins have a lower specific gravity than glass or metal and can have excellent mechanical physical properties such as excellent moldability and impact resistance. Plastic products made using such thermoplastic resins are quickly replacing conventional glass and metal products in fields such as electric and electronic products and automobile components.
Recently, there is a growing demand by users for an environmentally-friendly non-painted resin, as well as a growing demand by users for a metallic resin with a metallic like appearance imparted thereto by the resin itself without a coating process. Also, materials with low gloss or no gloss are increasingly being used in plastic materials for interior and exterior automobile components, in order to provide a luxurious appearance and touch.
A metallic appearance can be imparted to a resin without a coating process by adding metal particles to a resin composition. However, there can be appearance problems caused by flow-marks or weld-lines caused by the metal particles after an injection molding. Also, a mold should be additionally changed or the application is limited.
In order to solve these problems, Korean patent laid-open publication No. 2013-0078747 discusses controlling the shape or the aspect ratio of a metal particle. Also there is research directed to improving a surface coating material for a metal particle. However, even though these can provide some improvements, there also can be a limit on improving appearance problems, such as flow-marks or weld-lines caused by non-uniformity, agglomeration, and/or orientation of metal particles after an injection molding.
Therefore, in order to resolve the aforementioned problems, there is a growing need to develop a thermoplastic resin composition providing excellent appearance and physical properties such as impact resistance, light stability and the like, by controlling the degree of gloss and the shielding ability of a material itself.